ok so i have a 74 460 out of a tbird. has soem head work done but stock fuel pump stock intake and egrplat. i have the egr vale off and the hole blocked off were it was. i have a stock spec cam in it and not to much after market on it as of yet. coil wires headers thats about it besides the heads. got some port work done to them and new vales and springs supsoed to be over sized but never foudn out what size if the yare. but anywho ive gone threw p5 holley 4160c 600cfm vac sec carbs in liek 3 months. the prob is the keep flowing gas out of the vent tubes. seems to be a float prob but they are brand new out the box carbs. paid 264 bucks for it and gotta keep takeing them back every few weeks. i got a stock fuel pump new but stock fuel psi rateing. 2 fuel filters one befor and one after the pump. so nothing getting in the carb to mess it up. i even tryed a edlebrock carb and it flooded otu back on the highway. shot flames out the side pipes lol. nice light show at night but nott good on the engine. anywho jsut hopeing someoen can tell me if im mising soemtihng or if the carb isnt goona work on the engine. really in a tight spot cause i can only take the carb back onemore time and then they are gonna void my warrenty at autozone. liek i said this is the 5th on to do it and 6 countign the eldelbrock. hope someone cant help me. seems to me when it does it i can take the fule line off suck all the gas outa the fuel bouls and put the line bakc on and she runs good for 2 maybe 3 days and floods otu agin. and thats gettign way to anoying. figured ied ptu it up on here hopeing someones had the same prob. maybe its soemtihng i need to put on there to fix it im hopeing its something stupid. well thanks for ur time.

 

Sounds like your fuel pressure is too high which is forcing fuel into the carb past the float/valve.

You might have someone check the pressure coming out of the pump. It is possible that the pressure is wrong even on a new pump. Don't know what it should be with that model carb, maybe the dealer can tell you or someone on this webpage.

Perhaps you also need to adjust the float level if you haven't already.

Good Luck,

Jim henderson

 

hey thanks for the info ill try to borrow a pressure gauge and see what its pushing. i thin its 8 or 10 max psi. maybe ill put my presure regulator back on it. been driveing me nuts lol. even changed the pump twice. ill go try that only other option is to put on my 750 dubble pumper and my milage will go to hell cause its my work vehicle. but hey gess thats the price u pay for power. and i live by go big or go home so kinda works out i gess. ill try the presure and get back on ehre and let ppl know. thanks for the response.

 

o k put a pressure gauge on it pushin round 6psi. put a regulator on it set it at 5psi. draiend the carb dry to let the floats come down. fired it up ran like a dream agin. took it for a ride got about 2 miles from my hosue and it started to flood out yet agin. im at a loss here. dotn knwo what elce to try or what to do. pushing round 20lb's of vacume pressure at idle. good fuel pressure round 6 regulated down to 5psi. idels at round 600 rpm then when u take it for a ride and go around 2 or 3 miles it floods otu and wont stop flooding till u shut it down and drain the carb dry then runs liek a dream. its a modle 4160 holley cant adjust the needle valves or any of that. and odnt have the cash to tear it down and see if the floats are mess up. dont see hwo they ocudl be when its only liek 3 weeks old and got maybe 100 miles on it. the needles vales are caped off so u cant adjsut them. all i can adjsut is the air fuel mix and choke. well idel to. but yea i dont knwo what to do now at a loss. checked my timeign vacume,points all that. only flood out when im down aroudn 1000 rpm or at idle. then it puffs black smoke and runs liek tracsh liek the floats are stuck has anyone elce had this happen with a new holley. cause this is number 5. ive cleaned the tank out quite a few tiems when i first got the truck. all new fuel lines. a fliter befor the fuel pump and after a fuel pressure regulator. dont knw owhat elce it coudl be. well any help would be very welcome. really need to get it stra8 tonight cause i gotta be at work at 6am. well thansk for ur time ima go tinker with and and see if i can figure it out.

 

Holley carb is a pretty simple device, especially the floats. only a few things can cause the floats to not work.

float can have a hole in it (if brass) or gas soaked if plastic. only way to find out is tear carb apart.

something is causing the needle to stick open. did you use teflon tape on the threads? if so, you can be getting pieces of tape caught in the seat causing it to stay open. again you have to tear carb apart to find out. the Holleys needle and seat should unscrew form the top without having to remove bowl at least on the old models, not sure about new models.

the fuel pump is either putting out excessive pressure or malfunctioning. 5 psi is about max you want to see on a carb at all speeds, not just idle. also the diaghragm in the fuel pump might be not correct in that the fuel pump should have a spring that won';t let the diaghragm pump against a closed needle (simple explanation) so if this is not working correctly, the pump is going to build up pressure until the fuel is forced to go somewhere.

i would replace the fuel pump. to get 5 brand new carbs (as long as they are giving you brand new carbs and not just tearing apart the same carb and rebuilding it) that all flood is highly unlikely. i think you got a bad fuel pump instead.

replace that before you go any farther.

rgds
Mike

 

Have you called Holley on their tech line? whoever sold you the carb can get you the number but they can be quite helpful most of the time..

 

pumps brand new. umm i jsut whent otu and ploped down 290 bucks on a new one from a diff auto parts store. so far so good drove it to work today and home. runs like a champ smoekd a cavy and a yota lol. ppl never think i got that monster cramed under the hood. this time i put 2 new fuel filters after the pump just incase im getting crap comeing threw. btu liek i siad ive had the tank out befor. not even a year ago yet. and had a filter befor the pump and after.. pumps maybe got 500 miles on it tops. if i have any probs with this carb then ill got back to motor craft. but thansk for all the help. some thigns ill look into if i have further probs. lost the 264 bucks from the opther carb woudlnt give me a new one of a refund. pwell least the beast is alive. later all take it easy.

 

How did you check the fuel pressure? If you only checked it at idle, you still don't know what it builds to as you run down the road after a couple of miles. I find it hard to believe you got 5 carbs in a row and all were bad the same way. The odds are astro against it. Has the engine backfired at all? Even with the anti-backfire valve, you can still loose a power valve. On my '84 carb 460 with electric pumps, there is a return line to the tank for excess fuel.

 

Try a vented gas cap. Or just try running it around a while with it off and see how it acts.

 

i got a vented cap. and i reved her up some and got around 6psi at idle it was pushin round 5psi. i got mad at the carb threw it in the garage and whent out and got a 850 dubble pumper and put almsot 100 miels on it with no probs. put anouther filter on it just incase i missed something in the tnak when i had it out cleaning it.mine has no return never has had one even when it was in my 77f250. or the 74 tbird it came out of. the pump only has an inlet and a outlest. but so far so good on the new carb. and its never backfired. with this carb. rebuilt the engine right befor i bought the newone that was messing up. umm could it have had anythign to do with the egr valve not being hooked up. i took it off along itme ago cause the rubber was tore on it and blocked it off with some plates a buddy had on one of his trucks. but anywho thanks for all the help. hopefully this carb wont have any probs. i checked the filter i took off of it and replaced with a new one and it had nothing in it. no dirt or anythign so who knows. well thansk agin for the sugjestions.

 

Way to much carb for your engine and a DP on the street, in a truck will cause all kind of problems, the nastiest is poorer gas mileage.

 

Dumb question, but have you checked your float levels? There is a screw on the side of the bowl, passenger side that you can take off, it will reveal where teh fuel level is. The fuel should be just at or below the threads. The adjustment is the big screw and nut on top of the float bowl. Back the screw off 1/2 turn, use a 5/8" wrench to tighten the nut till fuel stops coming out of the bowl. I have found I can get pretty close with the setting by turning the nut till you are almost out of threads to go into the bowl.

I would venture a guess that the float setting is not your issue. Parts house carbs have a tendancy to be junk, but 5 in a row are impossible odds. I did not see you mention that you have a fuel filter? A little piece of junk will cause the needle and seat to not seal. If the Needle and seat gets stuck, or wont seal, rap it with a hammer to dislodge whatever is giving it grief, and free it up.

 

the carb i had didnt have the adjuster nuts on the bouls. they were caps instead of nuts. the one i have now has the sight plugs and the adjusting nuts. and i have 2 fulters one befor the pump and one after. the one after is a clear glass one so i can see if any junks building up in it. the oen i have on there now is doing good. no probs as of yet and ive been driveing it to work well on its way to 200 miles. driveing it up to my g/fs next week. thats around 50 miles. most of that highway so ill see if theres any probs with it if i drive that much stra8. works only about 15-20 miles from here so not a really good text but liek i said befopr it would go around 3 miles and mess up. but thanks for all the input guys this place is such a good site for ford guys to get togeather and help eachother out.